1. Field of the Invention
The present invention relates to an improved 9 mm cartridge casing. In particular, the present invention relates to an improved 9 mm cartridge casing having greater strength and reliability, which cartridge casing comprises:
a substantially hollow cylindrical casing of suitable metallic material having a length of from about eight hundred ninety thousandths of an inch (0.890 in.) to about nine hundred thousandths of an inch (0.900 in.), said casing having as its external dimensions:
a first end portion extending from about forty thousandths of an inch (0.040 in.) to about fifty thousandths of an inch (0.050 in.) from the first end thereof, and having an outer diameter of from about three hundred ninety-five thousandths of an inch (0.395 in.) to about four hundred and one thousandths of an inch (0.401 in.);
a first intermediate portion extending from about twenty-one thousandths of an inch (0.021 in.) to about forty-nine thousandths of an inch (0.049 in.) from said first end portion thereof, and having an outer diameter of from about three hundred thirty-three thousandths of an inch (0.333 in.) to about three hundred forty-eight thousandths of an inch (0.348 in.);
a second intermediate portion extending from about twenty-one thousandths of an inch (0.021 in.) to about forty-nine thousandths of an inch (0.049 in.) from said first intermediate portion thereof, and having an outer wall which increases in diameter from about a diameter of from about three hundred thirty-three thousandths of an inch (0.333 in.) to about three hundred forty-eight thousandths of an inch (0.348 in.) to about a diameter of from about three hundred ninety-five thousandths of an inch (0.395 in.) to about four hundred and one thousandths of an inch (0.401 in.) at a substantially constant rate of increase of from about thirty degrees (30.degree.) to forty degrees (40.degree.) from the centerline of said casing; and,
a second and opposite end portion extending for the remaining length of said casing, and having an outer wall which uniformly decreases in diameter from about a diameter of from about three hundred ninety-five thousandths of an inch (0.395 in.) to about four hundred and one thousandths of an inch (0.401 in.) to a diameter of from about three hundred seventy-two thousandths of an inch (0.372 in.) to about three hundred eighty thousandths of an inch (0.380 in.);
and as its interior dimensions:
a first interior portion extending from about one hundred fifteen thousandths of an inch (0.115 in.) to about one hundred twenty-one thousandths of an inch (0.121 in.) from the first end thereof, and having an inner diameter of from about one thousand seven hundred thirty-two ten-thousands of an inch (0.1732 in.) to about one thousand seven hundred forty-four ten-thousands of an inch (0.1744 in.);
a second interior portion extending for a minimum of at least about forty thousands of an inch (0.040 in.), and having an inner diameter of about from seventy-nine thousandths of an inch (0.079 in.) to about eighty-three thousandths of an inch (0.083 in.);
a third interior portion extending to about from about five hundred seventy thousandths of an inch (0.570 in.) to about five hundred ninety thousandths of an inch (0.590 in.) from said first end of the casing, and having an inner diameter which increases to from about three hundred fifty-two thousandths of an inch (0.352 in.) to about three hundred fifty-six thousandths of an inch (0.356 in.); and,
a fourth interior portion extending from said third interior portion to the second and opposite end of said casing, and having a constant inner diameter of from about three hundred fifty-two thousandths of an inch (0.352 in.) to about three hundred fifty-six thousandths of an inch (0.356 in.).
2. Description of Related Art
The nine-millimeter (9 mm) cartridge, introduced by Georg Luger in 1902 and called the 9 mm Parabellum, is believed to be the most widely used military pistol cartridge in the world. It is used by a number of law enforcement agencies in the United States and has been adopted by the U.S. armed services, using a 9 mm Beretta pistol, as the official sidearm.
The 9 mm cartridge is only slightly smaller in dimension than the 0.38 caliber cartridge developed by Colt and Browning in 1900. However, the 9 mm cartridge was better adapted to use in automatic weapons, where the larger rim of the 0.38 cartridge and the straight wall design would interfere with automatic mechanisms. Further, the straight wall, though it accommodated more interior space in the cartridge, could not safely be loaded with an equivalent charge or reloaded easily, because the thinner casing wall would fail.
In an effort to increase the speed and power of a fired cartridge, many users changed to larger diameter bullets, with larger cartridge casings. However, the larger cartridge casings were bulky and prevented the use of larger magazines, allowing rapid fire of multiple cartridges. In addition, the larger caliber bullets had significantly higher recoil and the ballistics of the larger bullet are more difficult to control.
The 9 mm cartridge, because of its wide acceptance and use, lower recoil, and because its tapered exterior and heavier-walled construction, became widely used, particularly in automatic and semi-automatic weapons.
The cartridge casing of a standard 9 mm cartridge casing, however, like the 9 mm NATO (North American Treaty Organization) round, was only nineteen millimeters (19 mm) in length. To increase the power of the round, manufacturers began lengthening the casing, first to twenty-one millimeters (21 mm), and more recently to twenty-three millimeters (23 mm). While such expanded sizes have permitted increased charge loading, the limits of the cartridge casing design prevent any further pressure increases in the loading, and it is common for cartridges to fail at such substantial pressures.